1. Field of the Invention
The present invention relates to a nozzle and a substrate processing apparatus using the same.
2. Description of the Related Art
Conventionally, the following process is known as a film deposition method in a semiconductor manufacturing process. In the process, one or more atomic layers or molecular layers are formed on a surface of a substrate such as a semiconductor wafer (which is hereinafter referred to as just a “wafer”) by causing a first reaction gas to adsorb on the surface of the wafer and then by switching a supplying gas from the first reaction gas to a second reaction gas to react with the first reaction gas on the surface of the wafer in a vacuum atmosphere. Then, a film is deposited on the substrate by repeating the above process many times so as to deposit the atomic layers or the molecular layers. This process is referred to as, for example, ALD (Atomic Layer Deposition) or MLD (Molecular Layer Deposition), which is an effective method that can respond to a demand of manufacturing a thinner film because the method can precisely control a film thickness depending on the number of cycles and achieve preferable uniformity of film quality across the surface of the wafer.
A film deposition of a gate oxide used in a gate of a MOS (Metal Oxide Semiconductor) transistor is cited as an example of preferable usage of such a film deposition method. For example, when depositing a silicon oxide film (SiO2 film), bis(tertiary-butyl-amino)silane (which is hereinafter referred to as “BTBAS”) gas or the like is used as the first reaction gas (source gas), and ozone (O3) gas or the like is used as the second reaction gas (oxidation gas).
For example, Japanese Laid-Open Patent Application Publication No. 2010-56477 discloses a film deposition apparatus to implement the ALD or MLD. The disclosed film deposition apparatus implements the film deposition method by placing a plurality of substrates on a circular turntable in a circumferential direction provided in a process chamber, in which multiple process areas that supply different reaction gases from reaction gas nozzles provided in a side wall of the process chamber are provided separately from each other in the circumferential direction, and by supplying the different reaction gases in the process areas while rotating the turntable.
In the meantime, as the substrates have been increasing in size in recent years, for example, when the substrates are wafers, film depositions are performed on substrates having a diameter of 300 mm. Hence, according to the configuration of the gas nozzle provided in the side wall of the process chamber as discussed above, the length of the gas nozzles becomes long because the gas nozzles need to extend from the side wall to the vicinity of the center of the turntable in order to supply the reaction gases to the entire surfaces of the wafers placed on the turntable. Accordingly, when base portions of the gas nozzles are fixed to the side wall of the process chamber, the moment of tip portions of the gas nozzles become great, which causes the tip portions to be likely to descend due to its own weight.
When the gas nozzles are long, discharge rates of the gases from the gas nozzles become greater at the base portions that are closer to gas supply sources than at the tip portions of the gas nozzles. This causes a problem of making density of the reaction gases lower in the central area than in the peripheral area. To solve the problem, Japanese Laid-Open Patent Application Publication No. 2010-135510 discloses a film deposition apparatus configured to be able to adjust a distance between a surface of a wafer and a gas nozzle in a lengthwise direction of the gas nozzle by adjusting an inclination of the gas nozzle to the horizontal axis.
In the meantime, high-k processes for depositing high dielectric films are often used in recent years. Gas species for film deposition used in the high-k processes have caused a problem of deteriorating film properties because the gas species have such poor resistance properties as source gases that the gas species cannot sustain the same condition in a high temperature in the process chamber as the condition in a low temperature, and further because self-decomposition of the gas species occurs in a gas phase before adsorbing on a wafer. More specifically, in cases where the gas nozzle is provided in the side wall of the process chamber and extends toward the center of the turntable, when a source gas is supplied from the side wall, the self-decomposition of the source gas occurs before the source gas reaches the tip portion of the gas nozzle due to the high temperature in the process chamber, and a sufficient film deposition is not performed at and around the center of the turntable, which causes a problem of deteriorating uniformity of film thickness across the surface of the wafer.
Such a problem cannot be solved by just adjusting the inclination of the gas nozzle as disclosed in Japanese Laid-Open Patent Application Publication No. 2010-135510, and using a nozzle structured to prevent the self-decomposition of a source gas is needed.